Thin plate manufacturing method and thin plate manufacturing apparatus

ABSTRACT

In order to obtain a thin plate manufacturing method capable of extremely increasing manufacturing efficiency by enlarging the production scale and remarkably reducing the manufacturing cost per unit area and an apparatus for manufacturing this thin plate, a method and an apparatus performing introduction of a substrate into a main chamber and discharge of the substrate from the main chamber through at least one subsidiary chamber ( 3, 4 ) adjacent to the main chamber ( 1 ) are employed when manufacturing a silicon thin plate by dipping a surface layer part of the substrate into a silicon melt ( 7 ) in a crucible ( 2 ) arranged in the main chamber ( 1 ) for bonding silicon ( 5 ) to the surface of the substrate.

TECHNICAL FIELD

The present invention relates to a thin plate manufacturing method and athin plate manufacturing apparatus, and more specifically, it relates toa silicon thin plate manufacturing method and a silicon thin platemanufacturing apparatus.

BACKGROUND ART

Silicon is employed for a public solar cell. While conversion efficiencyis decreased in order of single-crystalline silicon, polycrystallinesilicon and amorphous silicon, the cost is reduced in the aforementionedorder to readily implement a larger area. Among these, amorphoussilicon, which can be deposited from a raw material of SiH₄ on asubstrate of glass, plastic or metal by CVD (Chemical Vapor Deposition),is at a low cost and can be readily increased in area. The conversionefficiency is about 12% at the maximum.

As to single-crystalline silicon, an ingot having a diameter of 150 mm(6 inches) or 200 mm (8 inches) is manufactured by the CZ (Czochralski)method and can be increased in size, and the conversion efficiencythereof can exceed 15%.

As to polycrystalline silicon, a method of solidifying/growing the samefrom a liquid phase or a method of depositing the same from a vaporphase is researched. While polycrystalline silicon can be readilyincreased in area similarly to amorphous silicon, the conversionefficiency thereof is on an intermediate position between those ofsingle-crystalline silicon and amorphous silicon.

Each of the aforementioned various types of silicon manufacturingmethods increases the area, improves of the conversion efficiency andreduces the manufacturing cost. However, the unit generating costthereof is rather expensive as compared with the present large-scalepower generation system such as nuclear power generation or thermalpower generation, and the manufacturing cost must be reduced.

DISCLOSURE OF THE INVENTION

An object of the present invention is to provide a method ofmanufacturing a thin plate of silicon capable of remarkably increasingmanufacturing efficiency by enlarging the production scale whileensuring high quality and extremely reducing the manufacturing cost perunit area and an apparatus for manufacturing this thin plate.

The inventive thin plate manufacturing method is a method ofmanufacturing a thin plate by dipping a surface layer part of asubstrate into a melt of a substance including at least either ametallic material or a semiconductor material in a crucible arranged ina main chamber and solidifying the melt on the surface of the substrate.The substrate is loaded into the main chamber and unloaded from the mainchamber through at least one subsidiary chamber adjacent to the mainchamber.

When the atmosphere enters the main chamber having an inert gasatmosphere, silicon and oxygen react with each other if the melt is asilicon melt, for example, to cause Si loss and powder adhesion to theinner wall of the main chamber due to generation of SiO_(x). It ispossible to remarkably improve operating efficiency while reliablypreventing introduction of the atmosphere into the main chamber or thelike and ensuring high quality by employing the subsidiary chamber ashereinabove described for loading/unloading the substrate through thesubsidiary chamber. In other words, it is possible to directly preventintroduction of the atmosphere into the main chamber through thesubsidiary chamber when loading/unloading a large quantity of substratesinto/from the main chamber at high efficiency.

Switching means is preferably arranged between the main chamber and thesubsidiary chamber in preparation for a case of an unexpected situationor the like. When the switching means is set to be closed in anemergency, the degree of trouble can be reduced. Therefore, themanufacturing yield can be improved and a high-quality thin plate can beensured.

An airtight door, for example, can be employed for the switching means.A gate valve is a representative airtight door. The thin plate adheringto the substrate is a thin plate of polycrystalline siliconsolidified/grown on a growth surface of the substrate, for example.

A method of operating an apparatus formed by combining theaforementioned subsidiary and main chambers with each other is nowdescribed. When the substrate is loaded into the main chamber, thesubstrate is introduced into the said subsidiary chamber while closingthe switching means, then the atmosphere of the subsidiary chamber isequalized with that of the main chamber, and the switching means isthereafter opened for loading the substrate into the main chamber. Whenthe substrate to which a silicon thin plate, for example, is bonded isunloaded from the main chamber, the switching means is opened after theatmosphere of the subsidiary chamber is equalized with that of the mainchamber so that the substrate is unloaded from the main chamber into thesubsidiary plate, the switching means is closed, and the substrate isthereafter discharged.

Inert gas is preferably introduced into the aforementioned main chamber,and the pressure of the atmosphere in the main chamber is preferably setnot more than the atmospheric pressure.

When the pressure of the main chamber is set negative as describedabove, airtightness of the main chamber can be easily maintained, theusage of the inert gas can be reduced and the manufacturing cost can bereduced.

The aforementioned subsidiary chamber is constituted of a loadingsubsidiary chamber and an unloading subsidiary chamber so that thesubstrate can be loaded into the main chamber through the loadingsubsidiary chamber while the substrate to which the thin plate is bondedcan be unloaded from the main chamber through the unloading subsidiarychamber.

According to the aforementioned method, arrangement can be so made thatthe flow of loading the substrate and the flow of the substrate to whicha silicon thin plate, for example, is bonded do not interfere with eachother. The expression “the substrate to which the thin plate is bonded”indicates a state of the substrate dipped in the aforementioned melt fora prescribed time so that the melt is solidified on a growth surface ofthe substrate to form the thin plate present on the substrate. Thesolidified thin plate may be so displaced by an impact or the like thatthe thin plate is merely placed on the substrate. Further, the thinplate may adhere to the substrate as such after the aforementionedsolidification. More widely, a solid phase may grow to form the thinplate when the growth surface of the substrate is in the melt.

When the loading subsidiary chamber and the unloading subsidiary chamberas well as the main chamber are opened and closed by opening/closing theaforementioned switching means, switching timings of the switching meansfor the loading subsidiary chamber and the switching means for theunloading subsidiary chamber can be synchronized with each other.

Evacuation and inert gas purge of the subsidiary chamber requiring longduration are remarkable factors elongating the stroke (cycle time forthin plate manufacturing). Operations of the two subsidiary chambers areso synchronized with each other as hereinabove described that the twosubsidiary chambers can be operated in a time required for operating asingle subsidiary chamber.

In the aforementioned main chamber, the substrate is preferably mountedon a dipping mechanism so that the crystal growth surface of thesubstrate is opposed to a silicon melt, for example, for bonding thesilicon thin plate and the thin plate growth surface to which thesilicon thin plate is bonded is thereafter directed upward on a positionother than that immediately above a crucible for unloading the substratefrom the dipping mechanism along with the thin plate. The growth surfaceis opposed to the melt for preventing side surfaces other than thesurface for growing the thin plate from dipping in the melt to theutmost and suppressing the quantity of the melt solidified on theseportions, thereby improving the material utilization efficiency andreducing the degree of melt contamination. Further, the growth surfaceis so directed upward that the thin plate can be prevented from fallingfrom the substrate during transfer or due to impact at the time ofunloading the substrate.

As hereinabove described, the substrate is preferably mounted on anddemounted from the dipping mechanism on the position other than thatimmediately above the crucible. Mounting and demounting are so performedon the position other than that immediately above the crucible that themelt can be prevented from contamination caused by fine particlesfalling from engaging portions and entering the melt in the crucible inmounting and demounting.

Before the aforementioned thin plate is separated from the substrate,the substrate to which the thin plate is bonded is preferably cooled onat least one position in the main chamber, in the subsidiary chamber oroutside the chambers (outside the main chamber and outside thesubsidiary chamber).

According to the aforementioned method, the substrate is sufficientlycooled before reaching a separator for separating the substrate and thethin plate from each other, whereby the separator and peripheralequipment thereof are not exposed to high heat and deteriorated indurability or the like. Further, the thin plate and the substrate can beeasily handled after separation.

When the quantity of the melt in the aforementioned crucible is reducedto a prescribed level, the operation of the dipping mechanism can be sostopped as to refill the raw material in the crucible while notrestarting the operation of the dipping mechanism until the temperatureof the melt in the crucible and waving of the melt level are thereafterstabilized.

According to the above, temperature change of the melt and swinging ofthe melt resulting from refilling can be suppressed. Thus, the shape andthe quality of the thin plate can be maintained.

In the aforementioned refilling, the raw material can be loaded into themain chamber through a refilling subsidiary chamber adjacent to the mainchamber when refilling the raw material into the crucible.

Further, a plurality of substrates can be simultaneously introduced intothe aforementioned subsidiary chamber so that the substrates are loadedinto the main chamber one by one from the subsidiary chamber. Inaddition, the substrates to which thin plates are bonded may be unloadedone by one from the main chamber into the subsidiary chamber andsimultaneously discharged from the subsidiary chamber. Switching meanssuch as a gate valve may be interposed between the main chamber and thesubsidiary chamber, as a matter of course.

Evacuation and inert gas purge of the subsidiary chamber requiring longduration are remarkable factors elongating the cycle time. A pluralityof substrates are so introduced into the subsidiary chamber as describedabove that influence exerted on the stroke by an atmosphere controloperation in the subsidiary chamber can be relaxed.

A plurality of the aforementioned substrates may be simultaneouslyintroduced into the subsidiary chamber, simultaneously transferred to amounting standby position in the main chamber from the subsidiarychamber and shifted one by one from the mounting standby position to amounting position for the dipping mechanism. Further, the substrates maybe transferred one by one from a demounting position for demounting thesubstrates to which thin plates are bonded from the dipping mechanism toan unloading standby position in the main chamber for simultaneouslyunloading a plurality of substrates from the unloading standby positioninto the subsidiary chamber when a prescribed number of substrates areaccumulated on the unloading standby position.

According to the aforementioned method, the operation of the subsidiarychamber and that of the dipping mechanism can be so individuallyperformed that the stroke can be reduced.

The aforementioned dipping mechanism may perform demounting of thesubstrate to which the thin plate is bonded and mounting of a substrateto which a thin plate is newly bonded through the same operation.

Also according to this method, the substrate can be mounted on anddemounted from the dipping mechanism through a single action forreducing the stroke.

Another thin plate manufacturing method according to the presentinvention is a method of manufacturing a thin plate by dipping a surfacelayer part of a substrate held by a dipping mechanism into a melt of asubstance including at least either a metallic material or asemiconductor material in a crucible arranged in a main chamber andsolidifying the said melt on the surface of the substrate. According tothis thin plate manufacturing method, the dipping mechanism comprisesfirst substrate transport means for transporting the substrate in adirection for dipping and unloading the same into and from the melt,second substrate transport means enabling transportation of thesubstrate in a second direction different from the first direction andsubstrate rotation means capable of rotating the substrate by 360°, anddips the surface layer part of the substrate into the melt in thecrucible by controlling operations of the first and second substratetransport means and the substrate rotation means.

The aforementioned first substrate transport means can be formed byvertical transport means, and the second substrate transport means canbe taken as means for transporting the substrate in a direction ofprogressive movement. The aforementioned substrate rotation means andoperations in the aforementioned two directions are so combined witheach other that a controllable dipping operation can be naturallyperformed.

The aforementioned substrate rotation means preferably rotates thesubstrate by applying actuating force with reference to a supportingpoint of its rotation center on a power point different from thesupporting point and rotating the power point about the supportingpoint.

According to the aforementioned structure, the dipping operation and asubsequent operation of rotating the substrate upward so that the formedthin plate does not fall can be easily performed.

The aforementioned substrate is preferably mounted on a substratemounting member mounted to be rotatable about the supporting point androtatable about the power point.

According to the aforementioned structure, the substrate mounting membercan be easily rotated about the supporting point with excellentcontrollability in association with the power point. This substratemounting member is constituted of a pedestal in which the substrate isdirectly engaged and a pedestal support member fixing the pedestalbetween the supporting point and the power point, for example. Thepedestal support member is mounted to be rotatable along with thesupporting point as well as the power point.

A plurality of power points can be arranged with respect to a singleaforementioned support point.

In the case of this structure, the tolerance between an intended orbitand the actual orbit can be reduced by making control with the pluralityof power points and controllability can be improved due to the increaseddegree of freedom of the orbit when the inertia of the substratemounting member is large, for example.

In a series of operations of the aforementioned dipping mechanism movingthe substrate from a mounting/demounting position for mounting anddemounting the substrate to a position for dipping the substrate intothe melt, making the dipping operation on the substrate for dipping thesame and thereafter moving the substrate to the mounting/demountingposition for demounting the substrate, the direction of the horizontaloperation of the substrate in the dipping operation can be equalizedwith the operational direction for moving the substrate to themounting/demounting position.

According to the aforementioned method, the direction of movement maynot be reversed while dipping the substrate into the melt and directingthe same upward. Therefore, the time for directing the substrate upwardafter bonding the thin plate thereto can be shortened. Consequently, thetime when the formed thin plate may possibly fall can be shortened andthe recovery of the thin plate can be improved.

The aforementioned dipping mechanism can mount a first substrate on afirst position in the main chamber, move onto the crucible for dippingthe substrate into the melt, thereafter move, demount the firstsubstrate to which the thin plate is bonded on a second positiondifferent from the first position, mount a second substrate to which athin plate is newly bonded on the position, move onto the crucible fordipping the substrate into the crucible, thereafter move to the firstposition and demount the second substrate to which the thin plate isbonded on this position.

According to this method,.the dipping mechanism performs the dippingoperation in both of the forward and backward paths when reciprocatingon the crucible along a prescribed orbit, for example, whereby theoperating efficiency can be increased. Consequently, the stroke can bereduced.

The position of the melt level in the aforementioned crucible may bedetected for controlling the operation of dipping the substrate mountedon the dipping mechanism into the melt in response to the position ofthe melt level. For example, the depth for dipping the substrate mountedon the dipping mechanism into the melt may be controlled to be constantin response to the position of the melt level. The aforementionedcontrol of the dipping operation can be employed also when the thicknessof the substrate fluctuates.

According to this method, the level of the melt may not be kept at aconstant position but the frequency of refilling the melt can bereduced. Thus, the quality of the thin plate can be maintained and theoperating efficiency can be improved.

A plurality of dipping mechanisms may be employed for a singleaforementioned crucible for bonding the thin plate to the substrate.

According to the aforementioned method, the time for converting aconstant quantity of melt to the thin plate can be reduced.Consequently, the stroke can be reduced.

Still another thin plate manufacturing method according to the presentinvention is a method of manufacturing a thin plate by mounting asubstrate on a dipping mechanism provided in a main chamber, dipping asurface layer part of the substrate into a melt in a crucible arrangedin the main chamber and bonding a thin plate to the surface of thesubstrate, for manufacturing the thin plate by arranging a plurality ofdipping mechanisms with respect to the crucible.

As hereinabove described, a plurality of dipping mechanisms are soemployed that the time for converting a constant quantity of melt to athin plate can be reduced.

While a first dipping mechanism included in the aforementioned pluralityof dipping mechanisms performs a dipping operation, a second dippingmechanism different from the first dipping mechanism preferably performsat least one of operations of mounting the substrate, demounting thesubstrate to which the thin plate is bonded, temperature control of thesubstrate and movement of the substrate.

While the time of the dipping operation rate-determining the strokecannot be changed, the second dipping mechanism parallelly performsanother prescribed operation while the first dipping mechanism performsthe dipping operation so that the stroke can be reduced.

In every one of the aforementioned thin plate manufacturing methods, thetemperature of the substrate is preferably controlled before the same ismounted on the dipping mechanism. According to this method, the strokecan be reduced for improving the operating efficiency. The temperatureof the aforementioned substrate, generally controlled in the mainchamber, may alternatively be controlled in the subsidiary chamber.

A thin plate manufacturing apparatus according to the present inventionis a thin plate manufacturing apparatus for manufacturing a thin plateby mounting a substrate on a dipping mechanism provided in a mainchamber, dipping a surface layer part of the substrate in theaforementioned melt in a crucible arranged in a main chamber and bondinga thin plate to the surface of the substrate. This thin platemanufacturing apparatus comprises at least one subsidiary chamberadjacent to the main chamber through switching means.

According to this structure, the atmosphere of the subsidiary chambercan be evacuated and purged with inert gas to match with the atmosphereof the main chamber in response to introduction of the substrate intothe subsidiary chamber or loading in the main chamber. Therefore, it ispossible to maintain the main chamber in an inert gas atmosphere ofnegative pressure with high stability.

The thin plate manufacturing apparatus may have the aforementioned firstsubsidiary chamber and a second subsidiary chamber, the first subsidiarychamber may be a loading subsidiary chamber for externally introducingthe substrate and loading the same into the main chamber, and the secondsubsidiary chamber may be an unloading subsidiary chamber for unloadingthe substrate to which the said thin plate is bonded from the said mainchamber and discharging the same. The aforementioned first and secondsubsidiary chambers may be provided on positions opposite to each otherthrough the main chamber.

According to the aforementioned structure, interference between thesubstrate before bonding of the thin plate and the substrate afterbonding of the thin plate can be prevented and the flow of the substratecan be smoothed.

The thin plate manufacturing apparatus may further have a refillingsubsidiary chamber adjacent to the main chamber through switching meansfor supplying a refilling raw material to the main chamber through therefilling subsidiary chamber.

According to this structure, refilling can be performed whilemaintaining the atmosphere of the main chamber, whereby the time betweenstoppage of the dipping operation for refilling and restarting of thedipping operation can be reduced.

Another thin plate manufacturing apparatus according to the presentinvention is a manufacturing apparatus for manufacturing a thin plate bydipping a surface layer part of a substrate held by a dipping mechanisminto a melt of a substance including at least either a metallic materialor a semiconductor material in a crucible arranged in a main chamber andsolidifying the melt on the surface of the substrate. In this thin platemanufacturing apparatus, the dipping mechanism comprises first substratetransport means for transporting the substrate in a direction fordipping and unloading the substrate into and from the melt, secondsubstrate transport means enabling transportation of the substrate in asecond direction different from the first direction and substraterotation means capable of rotating the substrate by 360°.

According to the aforementioned structure, a controllable dippingoperation can be naturally performed by combining the aforementionedsubstrate rotation means and the transport means of the aforementionedtwo directions with each other.

The aforementioned substrate rotation means may have a mechanism forrotating the substrate by applying actuating force with reference to asupporting point of its rotation center on a power point different fromthe supporting point and rotating the power point about the saidsupporting point.

According to the aforementioned structure, the dipping operation and asubsequent operation of rotating the substrate upward so that the formedthin plate does not fall can be easily performed.

The thin plate manufacturing apparatus preferably further comprises asubstrate mounting member mounted to be rotatable about theaforementioned supporting point and rotatable about the power point formounting the substrate.

According to the aforementioned structure, the substrate mounting membercan be easily rotated about the supporting point with excellentcontrollability in association with the power point.

A plurality of power points may be arranged with respect to onesupporting point. Consequently, the dipping operation can be controlledwith excellent controllability also when the dipping mechanism isincreased in size to increase the size of the substrate mounting member,for example.

Still another thin plate manufacturing apparatus according to thepresent invention is a thin plate manufacturing apparatus formanufacturing a thin plate by mounting a substrate on a dippingmechanism provided in a main chamber, dipping a surface layer part ofthe substrate in the aforementioned melt and bonding a thin plate to thesurface of the substrate. In this thin plate manufacturing apparatus, aplurality of dipping mechanisms are provided with respect to thecrucible.

According to the above, a thin plate manufacturing apparatus of highefficiency can be constituted.

Every one of the aforementioned thin plate manufacturing apparatusesaccording to the present invention preferably comprises substratetemperature control means on a front stage position of the substratemounting position.

According to the aforementioned apparatus structure, the cycle time canbe reduced, the manufacturing efficiency can be improved and themanufacturing cost can be reduced.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram showing a thin plate manufacturing apparatusaccording to a first embodiment of the present invention.

FIG. 2 is a diagram showing an exemplary dipping mechanism of the thinplate manufacturing apparatus shown in FIG. 1.

FIG. 3 is a diagram showing another exemplary dipping mechanism of thethin plate manufacturing apparatus shown in FIG. 1.

FIG. 4 is a diagram showing a thin plate manufacturing apparatusaccording to a second embodiment of the present invention.

FIG. 5 is a diagram showing a thin plate manufacturing apparatusaccording to a third embodiment of the present invention.

FIG. 6 is a diagram showing a dipping mechanism of the thin platemanufacturing apparatus shown in FIG. 5.

FIG. 7 is a diagram showing the time series of thin plate manufacturingwith the thin plate manufacturing apparatus shown in FIG. 5.

FIG. 8 is a diagram showing a thin plate manufacturing apparatusaccording to a fourth embodiment of the present invention.

FIG. 9 is a diagram showing a dipping mechanism of the thin platemanufacturing apparatus shown in FIG. 8.

FIG. 10 is a diagram showing the time series of thin plate manufacturingwith the thin plate manufacturing apparatus shown in FIG. 8.

FIG. 11 is a diagram showing a dipping mechanism in a thin platemanufacturing apparatus according to a fifth embodiment of the presentinvention.

FIG. 12 illustrates a substrate holder.

FIG. 13 illustrates another substrate holder.

FIG. 14 is a diagram showing a state of using the substrate holder shownin FIG. 12.

FIG. 15 is a diagram showing a state of using the substrate holder shownin FIG. 13.

FIG. 16 is a diagram showing a thin plate manufacturing apparatusaccording to a seventh embodiment of the present invention.

FIG. 17 is a diagram showing a state of manufacturing a thin plate withthe apparatus shown in FIG. 16.

FIG. 18 is a diagram showing a thin plate manufacturing apparatusaccording to an eighth embodiment of the present invention.

FIG. 19 is a diagram showing the time series of thin plate manufacturingwith the thin plate manufacturing apparatus shown in FIG. 18.

FIG. 20 is a diagram showing a modification of the thin platemanufacturing apparatus according to the eighth embodiment of thepresent invention.

FIG. 21 is a diagram showing a thin plate manufacturing apparatusaccording to a ninth embodiment of the present invention.

FIG. 22 is a diagram showing the time series of thin plate manufacturingwith the thin plate manufacturing apparatus shown in FIG. 21.

FIG. 23 is a diagram showing a thin plate manufacturing apparatusaccording to a tenth embodiment of the present invention.

FIG. 24 is a diagram showing the time series of thin plate manufacturingwith the thin plate manufacturing apparatus shown in FIG. 23.

FIG. 25 is a diagram showing a thin plate manufacturing apparatusaccording to an eleventh embodiment of the present invention.

BEST MODES FOR CARRYING OUT THE INVENTION

Embodiments of the present invention are now described with reference tothe drawings.

(First Embodiment)

FIG. 1 is a diagram illustrating a thin plate manufacturing apparatusaccording to a first embodiment of the present invention. The thin platemanufacturing apparatus 10 shown in FIG. 1 has a main chamber 1 in whicha crucible 2 is arranged and two subsidiary chambers 3 and 4 providedadjacently to the main chamber. The crucible 2 in the main chamber 1reserves a silicon melt 7, and a dipping mechanism 30 for dipping asurface layer part of each substrate 11 in the silicon melt 7 isarranged. The main chamber is maintained at pressure slightly lower thanthe atmospheric pressure, i.e., negative pressure through introductionof inert gas. In the thin plate manufacturing apparatus shown in FIG. 1,Ar gas is introduced and the pressure is set to 700 Torr. This Ar gas,removing silicon oxides and other dust through a filter or the like inexhaust, can be recycled.

The subsidiary chamber 3 is a loading subsidiary chamber for loadingeach substrate. The subsidiary chamber 4 is an unloading subsidiarychamber for unloading the substrate 11 to which silicon 5 is bonded fromthe main chamber 1. The loading subsidiary chamber and the unloadingsubsidiary chamber are positioned to be opposed to each other throughthe crucible 2, thereby simplifying the flow of the substrates. However,the subsidiary chambers may not necessarily be opposed to each otherthrough the crucible. The two subsidiary chambers may be arranged on theside of the same wall of the main chamber depending on the structure orthe shape of a dipping mechanism described later. In this case, it isnot necessary to provide two subsidiary chambers but a single subsidiarychamber may be provided with an introduction line and a discharge line.The atmospheres of the subsidiary chambers are set to negative pressurein the same atmosphere as the main chamber, i.e., the inert gasatmosphere.

A thin plate manufacturing method is now described. When the mainchamber 1 is in operation, an airtight door 21 is opened for introducingeach substrate 11 into the subsidiary chamber 3 while closing anotherairtight door 23 between the subsidiary chamber 3 and the main chamber.Then, the airtight door 21 is closed, the subsidiary chamber 3 isevacuated, thereafter Ar gas is introduced and the atmosphere of thesubsidiary chamber 3 is equalized with that of the main chamber byequalizing the pressure with that in the main chamber 1. Thereafter theairtight door 23 between the subsidiary chamber and the main chamber 1is opened along the operation of the dipping mechanism in the mainchamber, for loading the substrate 11 into the main chamber.

In the main chamber, the dipping mechanism 30 grasps the substrate 11and transfers the same onto the crucible 2. Then, the dipping mechanismlowers the substrate 11, dips the surface layer part of the substrate 11in the silicon melt 7 and forms a silicon thin plate on the surface ofthe substrate 11. Thereafter the substrate 11 to which the silicon thinplate is bonded rises and separates from the crucible 2. While thesubstrate is dipped in the melt, the bonded silicon melt is cooled sothat a solid phase grows to form a prescribed silicon thin plate.

The substrate 11 formed with the silicon thin plate is unloaded into theunloading subsidiary chamber 4 through the airtight door 23 opened afterconfirming that the airtight door 21 of the subsidiary chamber 4 isclosed and the atmosphere of the subsidiary chamber is identical to thatof the main chamber. Thereafter the substrate 11 formed with the siliconthin plate is discharged through the airtight door 21 while the airtightdoor 23 is closed. In order to cool the silicon thin plate formed on thesurface of the substrate 11, a cooling apparatus accelerating coolingmay be provided on at least one portion in the main chamber 1, thesubsidiary chamber 4 or the exterior for cooling the substrate to whichsilicon is bonded with the cooling apparatus. There is a method ofsetting a cooling plate with cooling water as the simplest coolingapparatus for bringing the substrate into contact therewith forout-heating/cooling the same.

Any mechanism may be employed for the dipping mechanism 30 transferringthe substrate 11 and dipping the same into the silicon melt 7 in themain chamber 1. FIGS. 2 and 3 illustrate some dipping mechanisms. Thedipping mechanism shown in FIG. 2 makes supporting plates 36 travelalong a rail 32 for performing horizontal transfer. The dippingmechanism performs vertical transfer by vertically moving lifting units33 supporting the rail 32 and vertically moving along poles.

Each substrate 11 is mounted on a pedestal 31 coupled to each supportingplate 36 by a rod 38, and moves along traveling of the supporting plate36 on the rail 32. The lifting units 33 move down on the silicon melt 7in the crucible 2 thereby moving down the supporting plate 36, the rod38, the pedestal 31 and the substrate 11 along with the rail 32 anddipping the surface layer part of the substrate into the silicon melt.Consequently, silicon is bonded to the surface of the substrate.Thereafter the lifting units 33 rise so that the substrate separatesfrom the silicon melt. At this time, the horizontal movement, thevertical operation and the operation of inclining the substrate areperformed by control mechanisms independent of each other. Consequently,the substrate can enter the melt, move in the melt and escape from themelt along an arbitrary orbit and in an arbitrary inclined state. Atthis time, a personal computer generally programs a horizontal movementcommand, a vertical operation/movement command and an inclinationoperation command respectively and transmits the same to controllersthereby implementing an arbitrarily orbit as programmed. Further, thesubstrate to which silicon is bonded performs horizontal motion afterescaping from the melt, and is demounted from the pedestal on a positionseparating from the crucible. Since the silicon melt is at a hightemperature of 1400 to 1500° C. and silicon is evaporated, an adiabaticor cooled screen 37 is arranged on the crucible in order to protect thedipping mechanism such as the rail. The aforementioned horizontalmovement, the vertical operation movement and the inclination movementare individually driven by three motors in total allocated to theseoperations respectively. The aforementioned program controls theaforementioned three independent movements (operations) so that asilicon thin plate of a prescribed thickness is obtained incorrespondence to (a) fluctuation of the level of the melt and (a2)fluctuation of the thickness of the substrate.

The dipping mechanism shown n FIG. 3 makes each supporting plate 36having a guide hole travel along a rail 32. Vertically moving rails 34and 35 form shallow U-shaped orbits on the crucible so that a pedestalapproaches the silicon melt on the silicon melt 7. The upper end of eachrod 38 is travelably mounted on the rails 34 and 35.

The substrate 11 is mounted on the pedestal 31, and made to travel alongthe rails 32, 34 and 35. When approaching the crucible, the rails 34 and35 take orbits approaching the silicon melt along smooth arcs. At thistime, the rod approaches the silicon melt through the guide holeprovided in the supporting plate 36, for consequently dipping thesurface layer part of the substrate 11 into the silicon melt. Thereafterthe rails 34 and 35 take rising orbits. A subsequent movement is similarto that in the case of FIG. 2.

According to this embodiment, the quantity of oxygen or the likepenetrating into the main chamber following loading and unloading ofsubstrates can be reduced when manufacturing silicon thin plates in amass production scale. Therefore, formation of oxides in the siliconmelt in the crucible can be so suppressed that the quality of theproduced silicon thin plates can be ensured and the manufacturing yieldcan be further improved. Further, silicon evaporating from the crucibleso hardly forms oxides that maintenance itself can be simplified. Inaddition, durability of various types of devices in the main chamber canbe improved.

(Second Embodiment)

FIG. 4 is a diagram illustrating the flow of thin plate manufacturing ina second embodiment of the present invention. Referring to FIG. 4, asubstrate 11 is introduced into a main chamber (apparatus body) 1through a loading subsidiary chamber 3, and placed on a mountingposition of a dipping mechanism 30. The substrate mounted on the dippingmechanism is temperature-controlled, and the surface layer part thereofis dipped into a silicon melt. At this time, the substrate is dipped inthe silicon melt while facing the surface on which a silicon thin plateis grown toward the silicon melt. In other words, the substrate isdipped while directing a crystal growth surface downward. After thesubstrate is pulled up from the dipping position, the crystal growthsurface of the substrate is directed upward so that the formed siliconthin plate does not fall from the substrate by gravity. Further, thesubstrate is placed on a demounting position for demounting the samefrom the dipping mechanism while carrying the silicon thin plate.Thereafter the substrate carrying the silicon thin plate is unloadedinto an unloading subsidiary chamber 4. Thereafter the silicon thinplate is cooled and separated from the substrate.

Following the aforementioned manufacturing of the silicon thin plate,the quantity of the silicon melt in the crucible is reduced. In order tocompensate this, a silicon raw material is refilled. Therefore, arefilling subsidiary chamber 6 is provided adjacently to the mainchamber for loading the raw material into a refilling mechanism such asa refilling crucible 9, for example, through the refilling subsidiarychamber and preparing a silicon melt. The refilling mechanism refillsthis silicon melt in the crucible, for supplementing the silicon melt.An adiabatic chute or the like for feeding the silicon melt into thecrucible from the refilling crucible can be employed for the refillingmechanism, not to hinder the movement of the substrate around thecrucible. This refilling mechanism can hold the level of the siliconmelt in a prescribed fluctuation range, for example.

The aforementioned loading subsidiary chamber 3, the unloadingsubsidiary chamber 4 and the refilling subsidiary chamber 6 compriseairtight doors between the same and the main chamber as well as theexterior. Further, inert gas is introduced into the main chamber as wellas the aforementioned loading subsidiary chamber, the unloadingsubsidiary chamber and the refilling subsidiary chamber for maintainingthe same at prescribed pressure. The atmosphere pressure of the mainchamber and those of the respective subsidiary chambers aresubstantially equalized with each other. However, the pressure of themain chamber and those of the subsidiary chambers may be different fromeach other within a prescribed range.

Penetration of gas such as oxygen exerting bad influence onmanufacturing of silicon thin plates can be suppressed in massproduction by employing three subsidiary chambers as described above.Consequently, influence exerted on the operation can be suppressed bystably coping with an unexpected situation.

(Third Embodiment)

FIG. 5 is a diagram showing a thin plate manufacturing apparatusaccording to a third embodiment of the present invention. The thin platemanufacturing apparatus shown in FIG. 5 is characterized in thatsubstrates flow in a constant direction for manufacturing silicon thinplates. A loading subsidiary chamber 3 is provided on one side of a mainchamber 1, while an unloading subsidiary chamber 4 is provided on aposition opposite thereto through the main chamber. Gate valves 22 arearranged between the subsidiary chambers 3 and 4 and the main chamber,for ensuring airtightness in the main chamber.

A refilling subsidiary chamber 6 is also provided on the main chamber 1for ensuring stability of the atmosphere in the main chamber in loadingof a raw material along with an airtight door 23 arranged between thesame and the main chamber. The loaded raw material is introduced into arefilling crucible and melted, to be refilled into a crucible 7.

The schematic flow of manufacturing silicon thin plates is as follows:First, substrates 11 are externally introduced into the loadingsubsidiary chamber. The substrates may be introduced one by one or inplural. In the thin plate manufacturing apparatus shown in FIG. 5, thesubstrates 11 are loaded one by one from the loading subsidiary chamber3 into the main chamber 1 through the gate valve 22. In the mainchamber, each substrate is mounted on a dipping mechanism 30 on amounting position 19. The dipping mechanism 30 transfers the substrate11 toward a silicon melt 7 from one side and dips the same in thesilicon melt. Thereafter the substrate to which a silicon thin plate isbonded is demounted from the dipping mechanism and unloaded into theunloading subsidiary chamber 4 arranged on the other side through thegate valve 22. The dipping mechanism returns to the mounting position 19for the substrate during this time. The unloading subsidiary chamberholds a prescribed number of substrates 11 formed with silicon thinplates 5, and discharges the substrates from the apparatus after thesame reach the prescribed number.

FIG. 6 illustrates the aforementioned dipping mechanism in detail. Thisdipping mechanism 30 comprises vertically moving mechanisms 52 travelingalong a transverse shaft 51, and substrate holders 27 are suspended fromthe vertically moving mechanisms. Each substrate holder 27 comprises arotary support 55 rotated by a rotation mechanism 54 and a suspensionsupport 53. A pedestal 31 is supported between the rotary support 55 andthe suspension support 53. The pedestal 31 has an engaging groove 31 aengaging with each substrate at the central portion. Each substrate 11shown in FIG. 6 has a ridgy projection 11 a on the back surface thereofso that the ridgy projection 11 a and the engaging groove 31 a of thepedestal engage with each other to be integrated with each other.

The substrate 11 loaded into the main chamber is mounted on the dippingmechanism 30 on the substrate mounting position. In the substrate holder27 located on the left end in FIG. 6, the pedestal 31 engages with thesubstrate. The rotary support 55 is located in front of the suspensionsupport 53, and the position for supporting the pedestal is also locatedin front. As the vertically moving mechanism 52 travels rightward, therotation mechanism 54 rotates to locate the rotary support 55 leftwardbeyond the suspension support 53. According to this rotation, thepedestal 31 is located above the substrate 11. Consequently, a crystalgrowth surface of the substrate faces the silicon melt 7. Thereafter thesurface layer part of the substrate is dipped in the silicon melt, forgrowing a silicon crystal on the crystal growth surface. After thesubstrate is pulled up from the silicon melt, the rotation mechanism 54rotates again for locating the substrate above the pedestal. At thistime, the crystal growth surface of the substrate is directed upward.

The silicon thin plate can be prevented from falling from the substrateby employing the aforementioned dipping mechanism.

The time series of the aforementioned thin plate manufacturing is nowdescribed with reference to FIG. 7. FIG. 7 describes the thin platemanufacturing flow at intervals of 5 seconds. First, four substrates arecombinedly introduced into the loading subsidiary chamber. Then, theloading subsidiary chamber is evacuated. Thereafter the loadingsubsidiary chamber is purged with argon gas. The treatment up to thisstage is performed on the loading subsidiary chamber in common for thefour substrates. At this time, the unloading subsidiary chamber is alsosubjected to evacuation and argon gas purge.

Thereafter one of the substrates is transported into the main chamberand mounted on the dipping mechanism. The substrate istemperature-controlled, thereafter dipped in the silicon melt, andpulled up. Then, the substrate is unloaded from the dipping mechanism.Thereafter the second substrate is transported from the loadingsubsidiary chamber into the main chamber while returning the dippingmechanism to the original mounting position. At this time, the firstsubstrate formed with a silicon thin plate is unloaded into theunloading subsidiary chamber and held therein. The second to fourthsubstrates are transported into the main chamber and repetitivelysubjected to the same treatment as that for the first substrate, and theunloading subsidiary chamber holds the for substrates formed withsilicon thin plates when the fourth substrate is unloaded into theunloading subsidiary chamber.

These four substrates formed with the silicon thin plates aresimultaneously unloaded from the unloading subsidiary chamber. At thistime, a time reaching about 80 seconds has elapsed from the point whenthe four substrates have been first introduced into the loadingsubsidiary chamber. When simultaneously introducing the four substratesinto the loading subsidiary chamber, dipping the same one by one andsimultaneously unloading the four substrates, therefore, the stroke(cycle time) is 80 seconds and it follows that a treatment time of 20seconds is required per substrate.

In the manufacturing method according to this embodiment, the substratesare loaded from the loading subsidiary chamber into the main chamber andunloaded from the main chamber into the unloading subsidiary chamberindependently of each other. Therefore, the mechanisms for loading andunloading can be so simplified that reliability of the mechanisms of thethin film manufacturing apparatus can be improved.

(Fourth Embodiment)

FIG. 8 is a diagram showing a thin plate manufacturing apparatusaccording to a fourth embodiment of the present invention. Thisembodiment is characterized in that a direction for transferringsubstrates by a dipping mechanism and a direction from a loadingsubsidiary chamber toward an unloading subsidiary chamber intersect witheach other. The dipping mechanism transfers each mounted substrate ontoa crucible, dips the same into a silicon melt, and thereafter returns toan original mounting position 19. The apparatus mounts a new substrateon the dipping mechanism while demounting the substrate formed with asilicon thin plate. Consequently, the time can be reduced as comparedwith a case of separately performing mounting and demounting of eachsubstrate.

An apparatus capable of parallelly mounting and demounting thesubstrates on and from the dipping mechanism as described above isimplemented by a substrate mounting/demounting mechanism shown in FIG.9, for example. Referring to FIG. 9, a substrate formed with a siliconthin plate has returned to the mounting position 19. A ridgy projectionprovided on the back surface of the substrate 11 formed with the siliconthin plate is engaged into an engaging groove of a pedestal 31 formounting the substrate on the pedestal. A substrate transferor 39arranged in a main chamber transfers substrates 11 to the substratemounting position 19. The substrates 11 of the substrate transferor andthe substrate formed with the silicon thin plate are flush with eachother, and the substrate transferor engages a new substrate in theextensional direction of the engaging groove of the pedestal 31. At thistime, the substrate formed with the silicon thin plate is extruded bythe new substrate and demounted from the dipping mechanism. In thiscase, the positions for mounting and demounting the substratesrespectively are adjacent to each other or substantially identical toeach other. Therefore, the mounting position 19 also expresses thedemounting position.

FIG. 10 illustrates the time series of the aforementioned thin platemanufacturing. This manufacturing flow is identical to the manufacturingflow of FIG. 7 for the most part. The difference resides in that theapparatus demounts the substrate from the dipping mechanism, thenreturns the dipping mechanism to the original mounting position andthereafter mounts the second substrate on the dipping mechanism in theflow shown in FIG. 7 while the apparatus simultaneously and parallellymounts and demounts the substrates on and from the dipping mechanism inthe flow shown in FIG. 10. Therefore, time reduction can be implemented.In other words, the apparatus can simultaneously and parallelly mountthe second substrate on the dipping mechanism and demount the firstsubstrate from the dipping mechanism in the column of the elapsed timeof 35 seconds shown in FIG. 10. Therefore, the apparatus can reduce thestroke for manufacturing four silicon thin plates to 75 seconds. Thiscorresponds to a time of 19 seconds per silicon thin plate, and thestroke can be reduced by 1 second per thin plate as compared with themanufacturing flow shown in FIG. 7. Consequently, the manufacturingefficiency can be increased and the manufacturing cost can be reduced inthe field of solar cells etc. where the manufacturing cost is of greatimportance.

(Fifth Embodiment)

FIG. 11 is a diagram showing operations of a dipping mechanism in a thinfilm manufacturing apparatus according to a fifth embodiment of thepresent invention. All of arrangement of an insertion subsidiarychamber, an unloading subsidiary chamber and the dipping mechanism andthe flow of substrates are identical to those in the fourth embodiment.According to this embodiment, each substrate is moved from amounting/demounting position 19 for mounting and demounting thesubstrate toward a crucible and dipped therein for growing a thin plate,as shown in FIG. 8 of the fourth embodiment. Thereafter the dippingmechanism returns the substrate to the mounting/demounting position 19and demounts the substrate. The series of operations of the dippingmechanism are described.

A substrate holder 27 travels along a transverse shaft 51 and makes thesubstrate perform a vertical movement, a horizontal movement and arotational movement. A fulcrum 76 is present on an end of a suspensionsupport 53. A pedestal support member 59 fixing a pedestal 31 isrotatably mounted on the fulcrum 76, and the pedestal 31 for engagingwith the substrate is connected to the pedestal support member. Thepedestal support member 59 is connected to couple a power point 77located on an end of a rotary support 55 with the fulcrum 76. Rotationmechanisms 54 and 75 are present on an upper portion of the suspensionsupport 53, to support the rotary support 55 through a rotary arm 78. Itis possible to rotate the substrate by rotating the rotation mechanisms54 and 75. The pedestal support member is rotatably mounted on thesupporting point as well as on the power point.

Referring to FIG. 11, it follows that the dipping operation takes eitherone of the following directions of movement (revolution orbits): Arevolution orbit of an anticlockwise direction 64 or a clockwisedirection 65 on the plane of FIG. 11. The dipping operation along therevolution orbit in the anticlockwise direction 64 is in a cycle of thefollowing repetitive operations:

(1) To mount the substrate 11 on the substrate mounting/demountingposition 19.

(2a) To move the substrate 11 to a pre-dipping position (position 63 inthis case).

(3a) To dip the substrate 11 and move the same to a post-dippingposition (position 62 in this case).

(4a) To return the substrate 11 from the post-dipping position to thesubstrate mounting/demounting position 19.

(5) To demount the substrate 11 to which a thin plate is bonded.

In the case of the anticlockwise direction 64, the direction of thehorizontal operation in the dipping operation is rightward in FIG. 11,oppositely to the aforementioned return operation (4a).

On the other hand, the dipping operation in the clockwise direction 65is in a cycle of the following repetitive operations:

(1) To mount the substrate 11 on the substrate mounting/demountingposition 19.

(2b) To move the substrate 11 to a pre-dipping position (position 62 inthis case).

(3b) To dip the substrate 11 and move the same to a post-dippingposition (position 63 in this case).

(4b) To return the substrate 11 from the post-dipping position to thesubstrate mounting/demounting position 19.

(5) To demount the substrate 11 to which a thin plate is bonded.

When the revolution orbit is in the clockwise direction 65, thedirection of the horizontal operation in the dipping operation isleftward in FIG. 11, identically to the aforementioned direction of thereturn operation (4b).

As shown in the above, the pre-dipping positions and the post-dippingpositions are replaced with each other in the revolution orbits alongthe anticlockwise direction 64 and the clockwise direction 65. The angleof inclination of the surface of the substrate with respect to the levelof a melt on the pre-dipping and post-dipping positions is set to ±80°in this embodiment.

FIG. 12 is a diagram illustrating the substrate holder 27 travelingalong the transverse shaft 51 in detail. The fulcrum 76 is present onthe end of the suspension support 53. The pedestal support member 59 isconnected to couple the power point 77 located on the end of the rotarysupport 55 with the fulcrum 76. The pedestal 31 engaging with thesubstrate 11 is connected to the pedestal support member 59. Therotation mechanisms 54 and 75 are present on the upper portion of thesuspension support 53 for supporting the rotary support 55 through therotation arm 78. It is possible to rotate the substrate 11 by rotatingthe rotation mechanisms 54 and 75.

The simplest structure is a structure providing through shafts on thesupporting point and the power point. According to this method, however,the through shafts and the support physically interfere with each otherand hence it is impossible to rotate the substrate by 360°. Assumingthat the substrate is at an angle of rotation of 0° when the surfacethereof is directed immediately downward and the clockwise direction ofrotation in the dipping mechanism is the positive direction, forexample, it follows that the through shaft of the power point 77 and thesuspension support 53 collide with each other at an angle of about +90°.Therefore, the substrate rotation range is up to 80° in the positivedirection and up to −260° in the negative direction. The positivedirection and the negative direction of rotation are the directions ofrotation of the dipping mechanism. Description is made distinguishablyfrom arrows 64 and 65 in FIG. 11 indicating revolution of the dippingmechanism. On the other hand, it is possible to avoid interference withthe support by providing no through shaft at least either on thesupporting point or on the power point. In this case, the substrate isrotatable by 360°. However, the structure is complicated to deterioratethe cost and durability.

Operations of the dipping mechanism incapable of rotating the substrateby 360° are described. In this case, it is impossible to pass through+90° as described above. When dipping the substrate through therevolution orbit along arrow 64 in FIG. 11, it is necessary to rotatethe substrate clockwise by 260° in total from upward rotation (angle ofrotation=−180°) up to +80° while moving from the substratemounting/demounting position 19 to the pre-dipping position 63. In otherwords, the substrate cannot take the minimum angle of rotation but takesthe attitude at the pre-dipping position 63 by inversely rotating in adetouring manner. Thereafter the substrate is dipped while rotatinganticlockwise, and rotates by 100° in total up to −180° while returningfrom the post-dipping position 62 to the substrate mounting/demountingposition 19.

When dipped through the revolution orbit along arrow 65 in FIG. 11, thesubstrate must rotate clockwise by 100° in total from upward rotation(angle of rotation =−180°) up to −80° while moving from the substratemounting/demounting position 19 to the pre-dipping position 62.Thereafter the substrate subjected to dipping must rotate anticlockwiseby 260° in total from the post-dipping position 63 (angle ofrotation=+80°) up to −180° while returning to the substratemounting/demounting position 19.

In each of the aforementioned dipping operations, the substrate notrotating by 360° must be rotated by 260° in either one of thepre-dipping movement and the return movement. When the rotational speedis set to 3000°/min., 5.2 seconds are required for only the rotation, toremarkably deteriorate the stroke. Even if the rotational speed isimproved by increasing the power, durability measures are required, theweight of the dipping mechanism is increased and it is necessary tofurther increase the power, to remarkably increase the apparatus cost.

Operations of the dipping mechanism are described with reference to acase where the substrate is rotatable by 360°. When the substrate isdipped through the revolution orbit along arrow 64 in FIG. 11, thesubstrate rotates anticlockwise by 100° in total from upward rotation(angle of rotation =−180°) up to ÷80° while moving from the substratemounting/demounting position 19 to the pre-dipping position 63.Thereafter the substrate is dipped and rotates by 100° in total up to−180° while returning from the post-dipping position 62 to the substratemounting/demounting position 19.

When dipped through the revolution orbit along arrow 65 in FIG. 11, thesubstrate rotates clockwise by 100° in total from upward rotation (angleof rotation=−180°) up to −80° while moving from the substratemounting/demounting position 19 to the pre-dipping position 62.Thereafter the substrate is dipped and rotates by 100° in total up to−180° while returning from the post-dipping position 63 (angle ofrotation=+80°).

In each of the aforementioned dipping operations, it is necessary torotate the substrate by 100° during the pre-dipping operation or thereturn operation, in order to rotate the same by 360°. When therotational speed is set to 3000°/min., rotation is terminated in 2seconds.

As hereinabove described, the substrate is preferably rendered rotatableby 360° in consideration of the apparatus cost, durability and thestroke.

Thin plate recovery values in cases of manufacturing tin plates alongthe revolution orbit in the aforementioned clockwise direction 65 (thedirection of the dipping operation is identical to the return direction)and along the revolution orbit in the aforementioned anticlockwisedirection 64 (the direction of the dipping operation is opposite to thereturn operation) while equalizing the dipping orbits from thepre-dipping positions to the post-dipping positions and conditions witheach other are now described with reference to Table 1. TABLE 1Direction of Horizontal Operation in Dipping Operation Recovery (%)Identical to Return Direction 95 Opposite to Return Direction 92

Referring to Table 1, the case of the revolution orbit in theanticlockwise direction 64 (opposite to the return direction in Table 1)is inferior in recovery to the revolution orbit in the clockwisedirection 65 (identical to the return direction in Table 1) since thethin plates fall before returning to an exchange position after growth.This is because the direction of the horizontal operation of thesubstrates is so reversed before the substrates are directed upward thatthe thin plates are readily displaced from the substrates due toinertial force. In the clockwise case (arrow 65), the substratesregularly press the thin plates in the direction of the horizontaloperation thereof, so that the thin plates are hardly displaced from thesubstrates. Therefore, the direction of the horizontal movement beforethe dipping operation is preferably identical to the return direction tothe substrate mounting/demounting position 19.

(Sixth Embodiment)

FIG. 13 is a diagram illustrating a substrate holding part of a dippingmechanism in a thin plate manufacturing method according to a sixthembodiment of the present invention in detail. A fulcrum 76 is presenton an end of a suspension support 53. A pedestal 31 engaging with asubstrate 11 is connected to the fulcrum 76. With respect to thefulcrum, connection is made to a power point 77 located on an end of arotation support 55 on the side opposite to the substrate 11. Rotationmechanisms 54 and 75 are present on an upper portion of the suspensionsupport 53 for supporting the rotation support 55 through a rotation arm78. It is possible to rotate the substrate 11 by rotating the rotationmechanisms 54 and 75.

When employing the substrate holder 27 shown in FIG. 12, the fulcrum 76or the power point 77 is dipped in the melt 7 if the dipping operationis performed while inclining the substrate 11, as shown in FIG. 14.Therefore, it is impossible to remarkably incline the substrate 11.

When employing the substrate holder shown in FIG. 13, on the other hand,the substrate 11 can be set to a large angle of inclination whenentering a melt 7 or escaping from the melt 7, as shown in FIG. 15.Assuming that the substrate is at 0° when the same is directed downwardand the clockwise direction is the positive direction, it is alsopossible to make the substrate escape from the melt in a state of 90°,as shown in FIG. 15. At the time of escape from the melt, a pool of asilicon melt remains on a thin plate when an end of the grown thin plateseparates from the melt. This results from surface tension. Therefore,the substrate is so inclined at 90° when the end thereof separates fromthe melt that the melt is readily drained and the quantity of theremaining pool can be remarkably reduced.

(Seventh Embodiment)

FIG. 16 is a diagram illustrating a substrate holder 27 of a dippingmechanism in a thin plate manufacturing method according to a seventhembodiment of the present invention in detail. A pedestal 31 engagingwith a substrate 11 is connected to a pedestal support member 49, whichin turn is held by a suspension support 53 to be slidable about arotation axis 80. The rotation axis 80 is connected to a rotationmechanism 75 through power transmission mechanisms 81 and 82 such aschains or belts, for example. The substrate 11 is rotated by rotatingthe rotation mechanism 75.

When employing the substrate holder 27 shown in FIG. 16, a thin platecan be grown by enabling positioning before and after dipping into amelt by the rotation mechanism, a transverse moving mechanism and avertical moving mechanism while dipping the substrate into a melt andthereafter pulling up the same from the melt as shown in FIG. 17.

(Eighth Embodiment)

FIG. 18 is a diagram showing a thin plate manufacturing apparatusaccording to an eighth embodiment of the present invention. Thisembodiment is characterized in that two positions are provided formounting/demounting substrates on/from a dipping mechanism 30 forperforming dipping once in a unidirectional movement of the dippingmechanism and performing dipping once also in a return movementtherefrom. Mounting positions 19 also express positions for demountingthe substrates. According to the third and fourth embodiments, nodipping was performed in an intermediate stage of returning afterdipping by the dipping mechanism. According to this embodiment, however,dipping is performed both in forward and backward processes. In thiscase, a single loading subsidiary chamber and a single unloadingsubsidiary chamber are employed for transferring the substrates to thetwo mounting positions 19 from the single loading subsidiary chamber andtransferring the same from the two substrate mounting positions 19 tothe single unloading subsidiary chamber.

FIG. 19 is a diagram showing the time series of manufacturing accordingto this embodiment. This manufacturing flow is identical to that of FIG.10 for the most part. The difference resides in that the return time isrequired after the dipping operation in FIG. 10 while the substrates aremounted/demounted immediately after the dipping operation and thesubsequent dipping operation can be performed immediately after the samewithout a return operation in FIG. 19. Therefore, the stroke for formingsilicon thin plates on four substrates can be reduced to 65 seconds.This corresponds to 16 seconds per substrate.

FIG. 20 is a diagram showing a modification of the thin platemanufacturing apparatus employing the forward and backward processes ofthe dipping mechanism 30 for dipping. This case is characterized in thattwo loading subsidiary chambers 3 and two unload subsidiary chambers 4are provided. The structure can be simplified by employing this thinplate manufacturing apparatus since no mechanism is required fordistributing or collecting substrates 11 into or from two portions in amain chamber 1. Further, the rate of the working times in the subsidiarychambers in the overall operation can be reduced from one operation/fourdipping to one operation/eight dipping for further reducing the strokewithout remarkably increasing the length of the apparatus, bysynchronizing the operations of the two loading subsidiary chambers andthe operations of the two unloading subsidiary chambers with each otherrespectively.

(Ninth Embodiment)

FIG. 21 is a diagram showing a thin plate manufacturing apparatusaccording to a ninth embodiment of the present invention. Thisembodiment is characterized in that a mounting standby position 25 andan unloading standby position 26 are provided in a main chamber. Themounting standby position 25 and the unloading standby position 26function as buffers in supply of substrates 11 from a loading subsidiarychamber 3 to a dipping mechanism 30 and unloading from the dippingmechanism 30 to an unloading subsidiary chamber 4. Therefore, operationsof the respective subsidiary chambers and the operation of the dippingmechanism can be rendered independent of each other. Therefore, thestroke has no relation with the operations of the respective subsidiarychambers but is decided by only the operation of the dipping mechanism.The number of substrates capable of standing by on the mounting standbyposition must be in excess of the number of substrates simultaneouslysupplied from the subsidiary chamber. Similarly, the number ofsubstrates capable of standing by on the unloading standby position mustbe in excess of the number of substrates simultaneously unloaded intothe subsidiary chamber.

FIG. 22 is a diagram showing the time series of manufacturing in thethin plate manufacturing apparatus shown in FIG. 21. According to FIG.22, the dipping mechanism can parallelly continue the operation duringthe operations of the subsidiary chambers remarkably influencing thestroke. Consequently, the stroke for forming silicon thin plates on foursubstrates is reduced to 40 seconds, for implementing remarkablereduction. This corresponds to 10 seconds per silicon thin plate.

(Tenth Embodiment)

FIG. 23 is a diagram showing a thin plate manufacturing apparatusaccording to a tenth embodiment of the present invention. Thisembodiment is characterized in that two dipping mechanisms 30 a and 30 bare provided for a single crucible. The two dipping mechanisms are soprovided that the other dipping mechanism 30 b can progress anotheroperation when one of the dipping mechanisms, e.g. the dipping mechanism30 a performs a dipping operation. It is difficult to remarkably reducean actual dipping time in the dipping operation on the basis of crystalgrowth conditions for silicon thin plates. However, the stroke can behalved over the total dipping treatment time by the two dippingmechanisms progressing different operations in the same period.

FIG. 24 shows the time series of thin plate manufacturing in the case ofemploying two dipping mechanisms as described above so that the dippingmechanisms perform operations in a deviating manner for deviating thedipping operations thereof in the crucible from each other. According toFIG. 24, the stroke for forming silicon thin plates on four substratescan be reduced to 20 seconds. This corresponds to 5 seconds persubstrate. The dipping step time per substrate is extremely reduced ascompared with the dipping step time of 20 seconds per substrateaccording to the first embodiment.

Referring to FIG. 23, a cooling installation 26 is provided for thefollowing reason: When the cycle time is reduced as described above, thetime for natural cooling is also remarkably reduced. Therefore, thesubstrates carrying silicon thin plates may be not yet sufficientlycooled but in a high temperature state when discharged from theapparatus through an unloading subsidiary chamber 4. Therefore, thesubstrates may expose a mechanism for separating silicon thin plates 5from the substrates 11 outside the apparatus to a high temperature, tocause inconvenience on the separation mechanism or other mechanisms. Inorder to avoid this, the aforementioned substrates 11 can be cooled to asufficiently low temperature by providing a cooler 26 a on an unloadingstandby position 26 for holding the substrates 11 formed with thesilicon thin plates 5 in a main chamber 1 as shown in FIG. 23.

As hereinabove described, the number of substrates capable of standingby on the unloading standby position must be in excess of the number ofsubstrates simultaneously unloaded into the subsidiary chamber. Whencooling is also performed on the unloading standby position, however,substrates must be made to stand by/cooled in a number obtained byadding a number (time (seconds) necessary for cooling substrates/dippingstep time per substrate (seconds/number)) to the aforementioned number.Assuming that the time necessary for cooling the substrates is 10seconds and four substrates are simultaneously unloaded into thesubsidiary chamber, for example, the dipping step time per substrate is5 seconds and hence the number of standby substrates must be at least4+(10/5)=6.

According to this embodiment, the stroke can be remarkably reduced byarranging two dipping mechanisms for the single crucible 2. Further, theproblem of insufficient cooling of the substrates 11 formed with thesilicon thin plates 5 following reduction of the stroke can be solved byproviding a cooling apparatus on any position in the main chamber 1, theunloading subsidiary chamber 4 or outside the thin plate manufacturingapparatus.

While the single crucible is arranged in the main chamber 1 according tothis embodiment, a plurality of crucibles may alternatively be employedfor arranging a single dipping mechanism or a plurality of dippingmechanisms for each crucible. Further, a single dipping mechanism mayperform dipping treatment on at least two crucibles.

(Eleventh Embodiment)

FIG. 25 is a diagram showing a thin plate manufacturing apparatusaccording to an eleventh embodiment of the present invention. Thisembodiment is characterized in that a refilling installation is arrangedfor refilling silicon with respect to a silicon melt 7 in a crucible 2.

When manufacturing a large number of silicon thin plates by operating adipping mechanism, the level of the silicon melt 7 is lowered. It ispossible to cope with the change of the level position by grasping thelevel position by image processing or laser measurement and correctingthe orbit of substrates with respect to the silicon melt 7. When thequantity of the silicon melt 7 is remarkably reduced with respect to thecrucible 2, however, interference between the wall surface of thecrucible 2 and the orbit of the substrates or the bottom wall of thecrucible 2 and the orbit of the substrates results in a problem. Inother words, contact between the crucible 2 and the substrates resultsin a problem. If reduction of the quantity of the silicon melt 7 exceedsa prescribed range, therefore, the change of the level position cannotbe coped with by correcting the orbit of the substrates.

When reduction of the quantity of the silicon melt 7 exceeds theprescribed range, the dipping operation must be temporarily interruptedfor replenishing the silicon melt. As shown in FIG. 25, a refilling rawmaterial is introduced into a refilling crucible 9 through the refillingsubsidiary chamber 6 and heated to form a silicon melt. It is possibleto cope with reduction of the quantity of the silicon melt 7 by addingthe silicon melt to the crucible 2 at arbitrary timing. An airtight door23 is provided between the refilling subsidiary chamber 6 and the mainchamber 1. The refilling crucible 9 may be movable. A refilling chute orthe like may be arranged between the refilling crucible 9 and thecrucible 2. It is possible to avoid hindrance of movement of thesubstrates around the crucible 2 by rendering the refilling crucible 9movable or arranging a movable refilling chute.

Assuming that refilling is performed once for 500 silicon thin plates,for example, as to the timing for refilling, the raw material isrefilled once in 2500 seconds in the case of the ninth embodiment sincethe treatment time per substrate is 5 seconds. This time interval of2500 seconds is a time capable of introducing the raw material forrefilling from the refilling subsidiary chamber 6 into the main chamber1 and melting the same in the refilling crucible 9. Therefore, therefilling operation can be parallelly progressed independently of thetreatment of dipping the substrates in the crucible 2. The actualrefilling time corresponding to the total time for refilling the siliconmelt in the crucible 2 is about 30 seconds. Thereafter a melttemperature stabilizing time of about 10 minutes is required. Thesubsequent dipping operation cannot be performed for 630 seconds intotal. This time is something over 25% with respect to the mountingpitch of 2500 seconds, and hence the cycle time per substrate issomething over 5×1.25=6 seconds when manufacturing thin plates in orderof several days or several weeks.

It has been made possible to continuously manufacture silicon thinplates in order of several days or several weeks by performing refillingaccording to this embodiment.

(Twelfth Embodiment)

The temperature of the substrates is controlled after mounting thesubstrates in each of the embodiments heretofore described. This is forsuppressing the quantity of heat discharged by radiation to the utmostby suppressing the time lag between the temperature control of thesubstrates and dipping of the substrates into the melt. When heat lossresulting from radiation may not be taken into consideration due to aset temperature of not more than 700° C., for example, temperaturecontrol can be performed in a stage before mounting substrates. Further,temperature control is preferably performed in the stage before mountingsubstrates when a long temperature control time is required forhomogenizing temperature distribution or the like.

When executing temperature control in a front stage in the ninthembodiment, for example, the temperature control can be performed inparallel with the dipping operation. The cycle time can be reduced bythe substrate temperature control time (2 seconds×2 for foursubstrates). Further, the temperature control time can be increased byproviding a plurality of temperature control mechanisms before mountingthe substrates. In this case, the number of necessary temperaturecontrol mechanisms is at least (time (seconds) necessary for temperaturecontrol/dipping step time (seconds/number) per substrate). Assuming thatthe time necessary for temperature-controlling the substrates is 8seconds, for example, the number of necessary temperature controlmechanisms is at least two stages since the dipping step time persubstrate is 4 seconds.

A heater or the like can be employed for temperature-controlling thesubstrates. The heater can be arranged on the mounting standbypositioning the main chamber or the like.

The number of the substrates capable of standing by on the mountingstandby position must be in excess of the number of substratessimultaneously supplied from the subsidiary chamber. When thetemperature of the substrates is also controlled on the mounting standbyposition, however, substrates must be added by a number corresponding tothe number of stages for temperature-controlling the substrates, inaddition to the aforementioned number. Assuming that the number ofsubstrates simultaneously supplied from the subsidiary chamber is 4, forexample, the number of standby substrates must be at least (4+2) sincethe number of stages of the substrate temperature control mechanisms isat least 2 as described above.

While the embodiments of the present invention have been described inthe above, the embodiments of the present invention disclosed in theabove are merely illustrative, and the scope of the present invention isnot restricted to these embodiments of the present invention. The scopeof the present invention is shown by the description of the scope ofclaim for patent, and further includes all modifications within themeaning and range equivalent to the description of the scope of claimfor patent.

The thin plate manufacturing method and the thin plate manufacturingapparatus according to the present invention are so employed that theatmosphere of the main chamber can be stably maintained in a prescribedrange also in mass production since substrates are loaded into the mainchamber through the subsidiary chamber and subjected to the dippingtreatment. Therefore, it is possible to manufacture high-quality siliconthin plates with a high yield. Further, silicon thin plates can bemanufactured with high efficiency by arranging at least two dippingmechanisms for a single crucible. In addition, a long-term continuousoperation can be performed by refilling a silicon melt through thesubsidiary chamber thereby reducing a downtime required for refilling.Consequently, the cost for silicon thin plates can be reduced.

INDUSTRIAL APPLICABILITY

A large quantity of high-quality silicon thin plates can be stablyproduced continuously over a long time by employing the inventive thinplate manufacturing method and thin plate manufacturing equipment. Thus,a large quantity of silicon thin plates can be supplied at a low cost,and it is expected that the present invention is widely employed formanufacturing silicon thin plates for photovoltaic power generation, forexample.

1-45. (canceled)
 46. A thin plate manufacturing method of manufacturing a thin plate by dipping a surface layer part of a substrate held by a dipping mechanism into a melt of a substance including at least either a metallic material or a semiconductor material in a crucible arranged in a main chamber and solidifying said melt on the surface of said substrate, wherein said dipping mechanism comprises first substrate transport means for transporting said substrate in a direction for dipping and unloading the substrate into and from said melt, second substrate transport means enabling transportation of said substrate in a second direction different from said first direction and substrate rotation means capable of rotating said substrate by 360°, for dipping the surface layer part of said substrate into the melt in said crucible by controlling operations of said first and second substrate transport means and said substrate rotation means, and wherein said first substrate transport means operates to allow the substrate rotation means to be transported in the first direction.
 47. The thin plate manufacturing method according to claim 46, wherein said substrate rotation means rotates said substrate by applying actuating force with reference to a supporting point of its rotation center on a power point different from said supporting point and rotating said power point about said supporting point.
 48. The thin plate manufacturing method according to claim 46, mounting said substrate on a substrate mounting member mounted to be rotatable about said supporting point and rotatable about said power point.
 49. The thin plate manufacturing method according to claim 46, arranging a plurality of said power points with respect to one said supporting point.
 50. The thin plate manufacturing method according to claim 46, wherein said substrate rotation means rotates said substrate by applying actuating force to a shaft passing through its rotation center and rotating the shaft.
 51. The thin plate manufacturing method according to claim 46, equalizing, in a series of operations of said dipping mechanism moving from a mounting/demounting position for mounting and demounting the substrate to a position for dipping the substrate into said melt, performing a dipping operation on said substrate for dipping said substrate and thereafter moving to the mounting/demounting position for demounting said substrate, the direction of the horizontal operation of said substrate with an operational direction for moving the substrate to said mounting/demounting position when performing said dipping operation.
 52. The thin plate manufacturing method according to claim 46, wherein said dipping mechanism mounts a first substrate on a first position in said main chamber, moves onto said crucible and dips said substrate in said crucible, thereafter moves, demounts said first substrate to which a thin plate is bonded on a second position different from said first position, mounts a second substrate to which a thin plate is newly bonded on said position, moves onto said crucible and dips said substrate into said crucible, thereafter moves to said first position and demounts said second substrate to which the thin plate is bonded on said position.
 53. The thin plate manufacturing method according to claim 46, detecting the position of a melt level in said crucible for controlling the operation of said dipping mechanism dipping said substrate into the crucible in response to the position of said melt level.
 54. The thin plate manufacturing method according to claim 46, bonding the thin plate to said substrate with a plurality of dipping mechanisms with respect to one said crucible.
 55. The thin plate manufacturing method according to claim 46, performing temperature control of said substrate before mounting said substrate on said dipping mechanism.
 56. A thin plate manufacturing method of manufacturing a thin plate with a dipping mechanism dipping a surface layer part of a substrate into a melt of a substance including at least either a metallic material or a semiconductor material in a crucible arranged in a main chamber and unloading said substrate by solidifying said melt on the surface of said substrate, loading said substrate into said main chamber through at least one loading subsidiary chamber adjacent to said main chamber and unloading said substrate from said main chamber through at least one unloading subsidiary chamber adjacent to said main chamber, and wherein the dipping mechanism comprises first substrate transport means for transporting the substrate in a direction for dipping and unloading the substrate into and from said melt, second substrate transport means enabling transportation of said substrate in a second direction different from said first direction, and substrate rotation means capable of rotating the substrate by 360 degrees, wherein the first substrate transport means operates to allow the substrate rotation means to be transported in the first direction.
 57. The thin plate manufacturing method according to claim 56, wherein switching means is arranged between said main chamber and the subsidiary chamber, for loading said substrate into said main chamber and unloading said substrate from said main chamber along with switching of said switching means.
 58. The thin plate manufacturing method according to claim 57, wherein said subsidiary chamber is constituted of a loading subsidiary chamber and a unloading subsidiary chamber, for synchronizing switching timings of the switching means for said loading subsidiary chamber and the switching means for the unloading subsidiary chamber with each other when opening and closing said loading subsidiary chamber and the unloading subsidiary chamber as well as said main chamber by switching said switching means.
 59. The thin plate manufacturing method according to claim 56, introducing inert gas into said main chamber while setting the pressure of the atmosphere of the main chamber to not more than the atmospheric pressure.
 60. The thin plate manufacturing method according to claim 56, wherein said subsidiary chamber is constituted of a loading subsidiary chamber and a unloading subsidiary chamber for loading said substrate into the main chamber through said loading subsidiary chamber and unloading the substrate to which said thin plate is bonded from the main chamber through said unloading subsidiary chamber.
 61. The thin plate manufacturing method according to claim 56, mounting said substrate on said dipping mechanism, bonding the thin plate by opposing a thin plate growth surface of said substrate to the melt and thereafter directing the thin plate growth surface to which said thin plate is bonded upward on a position other than a position immediately above said crucible for demounting the substrate from said dipping mechanism along with the thin plate in said main chamber.
 62. The thin plate manufacturing method according to claim 61, simultaneously introducing a plurality of said substrates into said subsidiary chamber from outside, simultaneously loading the plurality of substrates into said main chamber from said subsidiary chamber, further transferring the substrates to a mounting standby position in said main chamber and shifting the substrates one by one from said mounting standby position to a mounting position on said dipping mechanism.
 63. The thin plate manufacturing method according to claim 61, transferring the substrate one by one from a demounting position for demounting the substrate to which said thin plate is bonded from said dipping mechanism into an unloading standby position in said main chamber and simultaneously unloading a plurality of substrates from said unloading standby position into said subsidiary chamber when said substrates accumulate by a prescribed number on said unloading standby position.
 64. The thin plate manufacturing method according to claim 61, wherein said dipping mechanism performs demounting of the substrate to which the thin plate is bonded and mounting of a substrate to which a thin plate is newly bonded through the same operation.
 65. The thin plate manufacturing method according to claim 61, equalizing, in a series of operations of said dipping mechanism moving the substrate from a mounting/demounting position for mounting and demounting the substrate to a position for dipping the substrate into said melt, performing a dipping operation on said substrate for dipping said substrate and thereafter moving said substrate to the mounting/demounting position for demounting said substrate, the direction of the horizontal operation of said substrate with an operational direction for moving the substrate to said mounting/demounting position when performing said dipping operation.
 66. The thin plate manufacturing method according to claim 61, wherein said dipping mechanism mounts a first substrate on a first position in said main chamber, moves onto said crucible for dipping said substrate into said crucible, thereafter moves for demounting said first substrate to which a thin plate is bonded on a second position different from said first position, mounts a second substrate to which a thin plate is newly bonded on said position, moves onto said crucible for dipping said substrate into said crucible and thereafter moves to said first position for demounting said second substrate to which the thin plate is bonded on said position.
 67. The thin plate manufacturing method according to claim 61, detecting the position of a melt level in said crucible for controlling the operation of said dipping mechanism for dipping said substrate into the crucible in response to the position of said melt level.
 68. The thin plate manufacturing method according to claim 61, bonding the thin plate to said substrate with a plurality of dipping mechanisms with respect to one said crucible.
 69. The thin plate manufacturing method according to claim 56, cooling the substrate to which said thin plate is bonded on at least one position in said main chamber, in said subsidiary chamber and outside the chambers.
 70. The thin plate manufacturing method according to claim 56, stopping the operation of said dipping mechanism when the quantity of the melt in said crucible decreases to a prescribed level for refilling a raw material into said crucible while not restarting the operation of said dipping mechanism until the temperature of the melt in the crucible and waving of the melt level thereafter stabilize.
 71. The thin plate manufacturing method according to claim 70, loading said raw material into the main chamber through a refilling subsidiary chamber adjacent to said main chamber when refilling the raw material into said crucible.
 72. The thin plate manufacturing method according to claim 56, simultaneously introducing a plurality of said substrates into said subsidiary chamber from outside and loading the substrates one by one from said subsidiary chamber into said main chamber.
 73. The thin plate manufacturing method according to claim 56, unloading the substrate to which said thin plate is bonded one by one from said main chamber into said subsidiary chamber and simultaneously discharging a plurality of substrates from said subsidiary chamber.
 74. The thin plate manufacturing method according to claim 56, performing temperature control of said substrate before mounting said substrate on said dipping mechanism. 